I had this happen to me. I rode by the quest giver and saw that he was still offering the quest, even though it said I was 5/10 battles. I accepted the quest again, and it reset back to 0/10. But I was at least awarded credit for future wins. Kind of annoying.

I found the same thing with the Beast of Fable quests -- if I left it partway complete overnight, then the next day the questgiver would offer me the quest again. If I took the new quest, it would overwrite the old one and erase my progress; if I didn't take the new quest, I couldn't get credit toward the old one anyway. My guess is the PvP one works the same way, although the reset is every week and not every day.

This happened to me for the first time this week. I didn't get credit for my first two wins, so I stopped queuing and opened a ticket. A GM got back to me today. They are aware of the issue, don't have a fix, and cannot award credit for the uncredited battles.

I didn't want to abandon and re-acquire the quest just in case a GM could give me credit, but now that I have that answer, I'll drop it and pick it back up. Irritating.

I am late to this party but if you ask me, it's terrible policy to force progress on a quest to reset, even if it is a weekly. I had collected four wins over the course of a few weeks because I was more concerned with lvling my pets than finishing the quest.

Then BOOM! One night, two of my Beasts of Fable quests that I had completed were reset even though I had just finished them an hour prior. What I didn't realize was at that point, my "What We've Been Training For" quest also reset. When I noticed, I opened a ticket hoping I could get my two pet bags of garbage and expecting my wins to be credited. But no dice on either. Today they told me they won't give me my BoF quest junk because they can't "see" that I finished them, which is fine I suppose. BUT the kicker is they won't credit me the pvp wins even though they are visible in the achieve! The premise is that the quest is a weekly and your progress resets weekly.

Which, to me, is total manure. The quest language does not imply in the least that there is a time frame in which to complete it. Imagine if your excess resources from the Barrens were deleted when the weekly reset? You'd be livid! It's the same thing, in my opinion. As someone who has frequently had to handle customer service issues, even when not working in customer service, I find stinginess from a company peddling virtual goods to be absolutely unacceptable. Ok I'm done ranting now...